Robert H. Richards IV, 47, was sentenced to eight years probation after pleading guilty to raping his 3-year-old daughter.

A du Pont family heir who pleaded guilty nearly six years ago to raping his 3-year-old daughter was never put behind bars because a Delaware judge ruled he “would not fare well” in prison, court records show.

Robert H. Richards IV — scion of the family who built the chemical empire and kin to the co-founders of a prestigious law firm, Richards Layton & Finger — was given eight years probation and was ordered to seek treatment after being convicted of fourth-degree rape in 2008, the records show.

Officials managed to keep the case away from the public spotlight until this month — when his ex-wife, Tracy Richards, filed a lawsuit seeking compensatory and punitive damages for abusing their daughter and son, the News Journal reported.